Follow-up to the Tailwind CSS v4 migration (#2969). Now that the UI is on Tailwind v4 (tailwindcss@4.3.0, CSS-first @theme), a few v4 features are worth adopting — prioritized by value for this dark-themed app.

1. color-scheme: dark for native controls (recommended first)

The app is dark-themed but native controls — input[type=date], the <select> dropdown arrow, scrollbars, autofill — still render light. Setting color-scheme: dark (v4.1 scheme-dark utility, or in the base layer) makes them render dark. Directly addresses the recurring "native control looks off" issues.

2. Native container queries (@container)

The media-card grids in globals.css (.cards-vertical, .cards-horizontal) use manual @media (min-width: 440px) breakpoints. Container queries (first-class in v4) would size cards to their container rather than the viewport — better inside slideovers/modals. Medium value.

3. field-sizing-content (v4.1)

Auto-growing textareas (rule Description, notification fields) without JS. Minor.

4. text-shadow-* (v4.1)

For title/badge text overlaid on poster images (MediaCard) — legibility without a background pill. Minor.

Not needed here: 3D transforms, radial/conic gradients, @starting-style (we already use Headless UI transitions).

Also deferred from the migration

• Remove the v3→v4 default border-color compat shim in globals.css (would require auditing bordered elements for explicit border colors).

Note: a reliable v4.2/v4.3 changelog wasn't available at migration time (npm doesn't bundle CHANGELOG.md; the GitHub releases page fetched unreliably), so confirm the newest point-release additions against the official changelog before relying on them. The items above are well-established v4.0/v4.1 features.